Last Night's TV: Kidult: P-Star Rising/BBC4The Model Agency/Channel 4

Essentially there is very little difference between Jesse Diaz, the father of Priscilla, the nine-year-old Cuban-American rapper who was the subject of last night's Kidult: P-Star Rising and, say, the dedicated father of a promising schoolgirl swimmer. Except that where the swimmer's dad would be accompanying his daughter to the municipal baths on a wet weekend in February, Jesse was taking Priscilla to a Harlem nightclub at 2am so that she could round out the night's entertainment.

The audience had that look on their faces – you would see it time and time again in Gabriel Noble's documentary – that people reserve for dogs that dance on their hind legs, but what the viewer soon came to understand about Priscilla and her rap alter-ego, P-Star (actually very little divided the two personas), was that she was not just a cutesy freak-show, a sort of rapping Shirley Temple, but a very talented and grounded individual. And did she need to be.

Firstly, there was her father, Jesse, who might himself have been a hip-hop contender back in the 1980s if he hadn't enjoyed the attendant ladies rather so much and got one of them pregnant – twice. Doris, mother of Priscilla and her older sister, Solsky (who has learning difficulties), was a heroin addict, leaving Jesse "to do what I had to do", which led him to a two-year prison term for dealing cocaine. After another two years on parole, Jesse managed to regain custody of his daughters, which is where we joined them, living in a one-room shelter in Harlem.

Despite being obvious – not least to Priscilla – that Jesse saw his daughter's burgeoning career as a way of fulfilling his own thwarted ambitions, as well as being a one-way ticket out of poverty, there was more to Jesse than the quintessential pushy stage parent. You did, however, question his judgement at times, as when he left the impressive Anthony "Hunc" Nixon of Hunc Records, who seemed genuinely interested in carefully nurturing P-Star's career, for an outfit called UBO Records. There was something about the $10,000 signing bonus and the lease of a car that felt like P-Star was being sold short, and sure enough UBO went bust, taking Jesse's dreams with them.

Jesse had the sort of New York street eloquence that any Scorsese fan would appreciate. You could imagine a young De Niro or Pacino delivering Jesse's line that "You get tired of the same old dreams. Dreams... dreams... I don't want to dream no more." It was Priscilla who told him to stop living in the past, although it wasn't all preternatural maturity and there were glimpses of the girl, aged 13 by the time Noble's quietly excellent documentary ended, being, well, a girl. Priscilla sweetly never quite gave up hope that her mother still thought about her, but even here these wishes were tinged with hard-earned wisdom. "My mum was real pretty... my mum and my aunt, but both became crackheads. Things happen..."

Having gone from rags to the promise of rap riches, we left the Diaz family in a less starry-eyed but more secure position: Jesse holding down two part-time jobs, Solsky going to college and P-Star starring in a children's TV show. Who knows, like many a child star before her, Priscilla may well go off the rails in her twenties, but I would be surprised. She has more sense in her little finger than the whole bunch of over-paid teenagers featured in this week's edition of The Model Agency.

It was London Fashion Week at the bubble that is Premier Models, and "Auntie Carole" and the team were busy importing human coat hangers from Paris, Milan and New York, and sending them out, armed only with a London A-Z, to up to 20 castings a day. This was more than Darya from Russia could cope with, moping sullenly about town and giving everyone a downer. "We love you," Annie (the teary agent who sounds like she's got a permanent cold) told Darya, having just confided to the camera that "we love to hate her, or hate to love her".

Coco, the Japanese model, managed to get herself into a situation on the King's Road, Chelsea, in broad daylight when it seemed that a group of boys were trying to take her mobile phone. Crisis over, and Coco reunited with her blower, Annie commented that "London's a dangerous city". She should try P-Star's neck of the woods. Meanwhile, Heidi, who can apparently earn up to £60,000 a day, went missing completely. Annie (again) suggested that Heidi could lose herself for up to a month, which I calculated as being lost potential income of up to £1.8m. Although I'm sure it doesn't work quite like that.

I'm not sure why I find The Model Agency quite so watchable, after all nobody says anything particularly witty, and all we're really seeing is a bunch of sales reps manning the phones (with the odd fag break). And then it struck me that the series may be filling a gap left by Big Brother, after all it is filmed in much the same way, with cameras in every nook and cranny, and what is absorbing are the Big Brother-style minutiae of expression and gesture, not to mention the rampant BB-style self-absorption. The other way to make documentaries is Gabriel Noble's way, slowly, over four years, detailing people like P-Star and lives you feel you might actually be able to give two hoots about.

g.gilbert@independent.co.uk